National Democratic groups have not spent a dollar on their own television or radio commercials promoting Mr. Jones, a former federal prosecutor. The party’s most popular campaigners, such as former President Barack Obama and Senator Bernie Sanders, independent of Vermont, have not set foot in the state. As Republicans in Washington pressure Mr. Moore to leave the race — with the Republican National Committee pulling its financing on Tuesday — Democratic leaders convey a stark public message to Mr. Jones: You’re on your own.

“It’s an Alabama race,” Senator Chuck Schumer of New York, the Democratic leader, said at a news conference on Monday, repeating the phrase three times for emphasis.

But the national Democrats’ ostensibly arm’s-length treatment of Mr. Jones belies a far deeper investment in the race. Senate Democrats covet Alabama’s Senate seat, passionately, but, as Mr. Schumer demonstrated, they are acutely aware of the risk of being seen as orchestrating the race from afar.

As Mr. Jones has gained ground against Mr. Moore, Democrats have taken measured steps to shore up his candidacy, helping Mr. Jones raise money and battering Republicans who have been slow to denounce their party’s embattled nominee. Several liberal activist groups have begun deploying organizers to Alabama to help prepare get-out-the-vote efforts for Mr. Jones in the Dec. 12 election.

And far from being shunned by the party, Mr. Jones’s top advisers have been open about which direction the shunning is going.

“Stay home, this is our race and we’ll decide it here,” said Giles Perkins, a former Alabama Democratic Party chairman and one of Mr. Jones’s strategists.

Mr. Jones, 63, has leaned heavily on his biography and legal record in the race, highlighting above all his role in prosecuting two of the Ku Klux Klan members who bombed the 16th Street Baptist Church in Birmingham in 1963. With an easy personal manner that contrasts sharply with Mr. Moore’s fire-and-brimstone style, Mr. Jones appealed to national Democrats early on as the kind of candidate who could win over unsettled voters to the right of center.

Mr. Jones also has a political network of his own to draw on in the race, and the few outsiders to stump for him have been personal acquaintances. Representative John Lewis of Georgia, a civil rights legend who got to know Mr. Jones as a United States attorney, campaigned for him this month. Former Vice President Joseph R. Biden Jr. rallied Democrats in Birmingham for Mr. Jones in October — Mr. Jones led Mr. Biden’s 1988 presidential campaign in Alabama.

Former Representative Parker Griffith, a conservative Democrat, said he spoke to Mr. Jones over the last few days and found him quiet and circumspect about the impact of the Moore scandal: “He said, ‘Well, let’s see how this plays out.’”

Mr. Griffith, who briefly became a Republican during the 2010 campaign, said Mr. Jones was still struggling against Alabama’s intense suspicion of the Democratic label. He said even bringing in Mr. Biden may have been a mistake.

“The Democratic brand, in Alabama, is poisonous,” Mr. Griffith said, adding: “Some of us said, my God, when you see Biden, you see Obama.”

For now, most Democratic leaders are happy to stay out. For all his public caution, Mr. Schumer has been effusive about the Alabama campaign in private, according to people who have spoken with him. Mr. Schumer has told allies he believes the race is now clearly winnable for Mr. Jones, but that Democrats must take pains not to nationalize the contest in a way that might offend voters in a deeply conservative state.

Still, in front of reporters, Mr. Schumer could not fully contain his excitement this week about the prospect of snatching away a Senate seat in one of the country’s reddest states. He gushed about Mr. Jones’s financial dominance over Mr. Moore, who has struggled to rally Republican donors.

If the Republican Party’s national reputation appears to hinge on the fate of Mr. Moore’s candidacy, the stakes in Alabama have grown nearly as high for Democrats. Democrats face forbidding Senate races in 2018, when they must defend several seats in Republican states and pick up three seats to win a majority in the chamber. At the moment, Democrats appear to have a good chance of winning only two Republican-held seats, in Nevada and Arizona.

An upset in Alabama would change that, transforming the challenge of winning a Senate majority from a seemingly impossible task into merely an extremely difficult one.

Mr. Jones’s campaign seems to recognize the stakes: Flush with optimism, the Democrat has turned to a hold-the-ball approach since a number of women emerged to recount their experiences with Mr. Moore when they were teens.

Mr. Jones decided not to travel to Washington on Tuesday night for a $500 per-person cocktail party fund-raiser headlined by such Democratic luminaries as Senator Kamala Harris and Eric H. Holder Jr., the former attorney general, because he saw no reason to do anything that could let Republicans redirect the focus of the campaign from Mr. Moore.

Instead, Mr. Jones released campaign commercials featuring voters who said they were Republicans supporting his candidacy. One video implored Alabamians: “Don’t vote for the party. Vote for the man.”

And discussions among Democrats about bringing in former President Bill Clinton, who has his own history with sexual impropriety, have been shelved as part of Mr. Jones’s attempt to keep a local focus for the duration of the campaign.

Mr. Jones, however, has benefited for months from an unheralded campaign by Democrats in Washington to direct money to his campaign, fueling his strong advantage on television. Mr. Jones has aired nearly $2 million in commercials, compared with about $300,000 for Mr. Moore.

This month, Representative Terri Sewell, the only Democrat in Alabama’s federal delegation, hosted a fund-raising event for Mr. Jones at a townhouse that is home to the Congressional Black Caucus Institute, with Senator Chris Van Hollen of Maryland, the chairman of the Democratic Senatorial Campaign Committee, in attendance.

Last weekend, as Mr. Moore fought for his political survival, the Human Rights Campaign, a national gay rights group, held a “Mimosas With a Purpose” fund-raiser for Mr. Jones at a private home in Washington.

State Representative Anthony Daniels, the Democratic leader in the Alabama House of Representatives, urged Mr. Jones to communicate an affirmative message about policy, rather than focusing on the accusations against Mr. Moore.

“The best thing we can do is keep it positive and talk about where Doug stands, and where he is on the issues, and not get down in the mud,” Mr. Daniels said.

Beyond the plain value of winning the Senate seat, Democrats also sense a larger symbolic test in Alabama: Should Mr. Jones prove unable to defeat Mr. Moore, it would be a stark verdict on his party’s limitations in the Deep South. Democrats have not won a major statewide election in Alabama since 2006, or elected one of their own to the Senate in a quarter-century.

But Democrats believe the Moore scandal may have opened an unusually wide path to victory in a state that is typically polarized along racial lines. Mr. Perkins said many white voters would be newly willing to consider Mr. Jones.

If not, Mr. Perkins said, “some folks just aren’t going to show up.”

A version of this article appears in print on , on Page A1 of the New York edition with the headline: Just Send Cash, Alabama Democrat Tells Party. Order Reprints | Today’s Paper | Subscribe